Milk has long been an important part of the human diet, but more recently has become somewhat of a pariah in the world of exercise and bodybuilding mainly because of the anti-fat movement.
Evidently, the allegation that milk consumption leads to higher body fat is inaccurate. Even though milk does contain fat, reasonable milk consumption mitigates the concern for weight gain while low-fat and skim milk are excellent alternatives that reduce fat consumption, while still providing the great nutritional value of milk.
Some of this great nutritional value comes from milk’s high-quality protein, essential vitamins and minerals that have many biological functions that positively impact human health.
Unique protein blend generates abundant muscle growth
Many scientific studies have shown that providing protein after resistance exercise optimizes muscle growth. It has also been demonstrated that muscle growth is influenced by the type of protein consumed, where rapidly absorbed protein generates a quick pulse of muscle protein synthesis, while more slowly absorbed protein produces a steadier increase in muscle protein production. Since milk contains slow and rapidly absorbed protein, casein and whey protein— which are both loaded with the muscle-building amino acid leucine—it should support both short and long-term increases in muscle protein levels, providing a greater overall level of muscle growth. This increase in muscle protein is due to the fact that leucine potently activates the extremely important nutrient-sensing molecule mTOR, which directly activates muscle protein synthesis while preventing muscle protein breakdown. Proving milk’s ability to robustly increase muscle protein synthesis, a study by Hartman et al confirmed that dairy proteins found in milk were superior in eliciting an increase in overall muscle protein synthesis compared to soy protein, where they found a more rapid and prolonged increase in leucine levels in the group that ingested milk.
Consuming milk after your workout supports longer protein synthesis
Since the milk protein casein is digested and absorbed slowly, it causes a slower elevation of the muscle-building amino acid leucine over a longer period of time. Therefore, milk is a great choice for boosting post-exercise muscle protein synthesis, as intense weightlifting combined with a steady source of leucine increases muscle protein synthesis for at least 24 hours. Demonstrating this fact was a study by Res et al that assessed the ability of the milk protein casein to support extensive periods of muscle protein synthesis after weightlifting. The study looked at healthy young males split into two groups, with one group receiving 40 grammes of casein hours after weightlifting while the control group received a placebo with no casein. The group that received casein showed greater muscle protein production well after exercise, highlighting the ability of milk ingestion after exercise to stimulate muscle protein synthesis for long periods of time. Most importantly, this greater level of muscle protein synthesis increases muscle size, as the study by Hartman et al measured greater type I and type II muscle fibre size after performing a resistance exercise programme while consuming milk after each workout.
Potent mix of fat-burning calcium and muscle-building vitamin D
Many scientific studies have shown that the inclusion of dairy products, like milk, in weight-loss diets accelerates the reduction of fat mass while increasing lean body mass. Since milk is loaded with calcium, which indirectly activates the enzyme AMPK and turns up fatty acid oxidation, scientists speculated that calcium was a major contributor to milk’s ability to reduce fat mass. Furthermore, milk is fortified with vitamin D, a steroid-like vitamin with numerous muscle-promoting properties coming from its testosterone-like chemical structure and function, which most likely makes vitamin D one of the more crucial components in milk that boosts muscle growth.
Milk fat increases testosterone levels
One of the most promising bioactive components in milk is conjugated linoleic acid (CLA). CLA is a mixture of polyunsaturated fatty acids derived from the omega-6 essential fatty acid linoleic acid. CLA’s major anabolic property comes from its ability to augment testosterone production. In a study by Macaluso et al, CLA supplementation in combination with resistance exercise generated a greater increase in testosterone when compared to just exercise alone. While these findings suggest that CLA supplementation increases testosterone levels, most of the molecular details are unclear. However, another study by Chen et al may have uncovered at least one of the molecular mechanisms generating CLA’s ability to trigger testosterone production. In this study, they show that CLA possesses anti-aromatase activity— which would directly increase testosterone production, as aromatase inhibition would prevent the conversion of testosterone into the estrogen-like compound estradiol, ultimately boosting the quantity of testosterone.